Many industrial components such as wires, cables and medical tubing are continuously marked at high speed. For example, continuous substrates, such as sheathed wires, are often marked by directing them from a feed spool through a banding device which deposits an ink onto sheathing of the wire, either intermittently or as a continuous coating. The wire is then exposed to the atmosphere for a period of time sufficient to allow the ink to bond to the sheathing and thereby mark the wire before being wound onto a take-up spool. Preferably, wires are marked at speeds of up to, or greater than, about 3,500 feet per minute.
This production method typically employs organic solvent-based inks. However use of these inks often causes release of hazardous material, such as ketones, as gas and/or liquid wastes. Ketones, for example, have been linked to human respiratory problems and are believed to damage the ozone layer.
One attempt to reduce the release of hazardous material during marking of industrial components is to substitute organic solvent-based inks with aqueous-based inks. For example, release of hazardous organic solvents can be substantially reduced or eliminated by substituting organic solvent-based inks with aqueous-based inks. However, water has a lower vapor pressure than most organic solvents. Therefore, aqueous-based inks typically require a longer drying period than do other inks.
Longer drying periods during marking of a continuous substrate, such as wire, are generally obtained by substantially reducing the rate of speed at which the substrate travels between a feed spool and a take-up spool, or by increasing the distance between the point of ink deposition and the take-up spool. However, diminishing the speed at which the substrate is marked significantly reduces the efficiency of production. On the other hand, increasing the distance between the point of ink deposition and subsequent take-up of the substrate is bulky.
Thus, a need exists for a system and method for marking continuous substrates, such as sheathed wire, cables and medical tubing, with an aqueous-based ink which minimize or overcome the above-mentioned problems.